Flow does not catch invalid switch statements

[ayroblu]

Posting here, cause this caused a production incident at our company. For the most part we're "fine" with our usage of flow, but this is one of the more serious bugs

Flow version:
0.220.1

Expected behavior

Incorrect switch case statements should throw an error

Actual behavior

Switch case statements are allowed to do anything

• Link to Try-Flow or Github repo: link

Specifically see this part:

Note the usage of "random_access"

[gkz]

Thanks for the report. For now, if using the disjoint object union pattern, stick to using literal types 'foo' directly rather than using typeof X.Foo, both when defining the type and when refining it (e.g. in a switch).